Portable electronic devices are increasingly being used for accessing content, applications and functionalities. For example, a portable electronic device may include a touch-sensitive screen that enables one to interact directly with what is displayed. The touch-sensitive screen can be used to activate a function of the electronic device or otherwise interact with a user. Users typically use the touch-sensitive screen in two basic orientations, namely a portrait orientation in which the screen is viewed vertically and a landscape orientation in which the screen is viewed horizontally.
A portable electronic device may include an accelerometer to assist with portrait-to-landscape rotations and landscape-to-portrait rotations of its screen. The accelerometer of the device measures device orientation relative to the gravity of Earth and, then, rotates the screen accordingly. Due to the limits of physical law, the orientation cannot be resolved when the device lies flat relative to the surface of the ground. In fact, automatic screen rotation often doesn't work when the device is more horizontal than vertical relative to the surface of the ground. Many users, particularly those who understand the physical limitations of conventional screen rotation, avoid the problem by positioning the device vertically whenever screen rotation is desired.